Pour 1/4 cup of powdered dish detergent into a bowl. Add water slowly and stir until a paste forms. Cover the water marks with the paste and then scrub with a nonabrasive sponge. Allow the solution to rest for 20 minutes before you rinse and dry off the shower.
Soak a microfiber cloth in white vinegar if water spots remain. Wipe the shower down with the vinegar and remove tough water spots with a plastic scrubber. Let the vinegar set for 15 minutes and then rinse the surface with clean water. Dry the shower with a towel afterward.
Combine 1 cup of baking soda and 1 cup of white vinegar in a bowl to create a paste to remove tough water marks. Rub the paste over the hard water marks on the shower. Allow the paste to rest for 15 to 20 minutes and rinse it off with clean water. Dry the shower surface with a towel to prevent the marks from returning.
Fill a clean bucket with 1 gallon of hot water and add 1 tablespoon of ammonia if the water marks remain. Dampen a nonabrasive sponge in the solution and wipe the shower surface to remove the marks. Rinse the shower with clean water and dry it thoroughly.
Clean water marks from chrome shower fixtures by soaking a washcloth with rubbing alcohol. Rub the washcloth over the fixtures to restore the shine. Wipe the fixtures with a dry washcloth.